The liquid crystal display apparatus is thin and light in weight, and therefore finds wide applications as a display of a portable information terminal. The liquid crystal display apparatus comprises a liquid crystal panel including a pair of substrates between which the liquid crystal is held. The apparatus may further comprise a color filter or a polarizer. The apparatus is of two types, a transmission-type display apparatus in which light is transmitted through the substrate pair and the liquid crystal, and a reflection-type display apparatus in which light is transmitted through one of the substrates and the liquid crystal and reflected on the other substrate. In both types of liquid crystal display apparatus, the phase is modulated when light is transmitted through the liquid crystal. Black and white are displayed by the light transmitted through the color filter and transmitted or shielded by the polarizer. The arrangement of a plurality of dots forms character information or image information.
The liquid crystal itself is a light-receiving element incapable of emitting light, and the information is difficult to recognize visually with the liquid crystal alone. Generally, therefore, an illuminating device is combined with the liquid crystal panel. In the transmission-type liquid crystal display apparatus, the illuminating device is arranged on the back of the liquid crystal panel, while the illuminating device is arranged on the front of the liquid crystal panel in the reflection-type liquid crystal display apparatus. In the reflection-type liquid crystal panel, the illuminating device is not required, as long as sunlight or the light from a room lamp is radiated on the liquid crystal panel. In an environment hardly reached by light, however, the reflection-type liquid crystal panel, like the transmission-type liquid crystal panel, requires the illuminating device.
A conventional linear illuminating device is available which comprises a light source and a rod-like photoconductor entered by the light from the light source through a plane of incidence and emitting the light by way of a long exit plane. A conventional planar illuminating device is also available which comprises a light source, a rod-like photoconductor and a plate-like photoconductor entered by the light from the rod-like photoconductor through a plane of incidence and emitting the light through a wide exit plane (Japanese Unexamined Patent Publication No. 10-260405).
In recent years, demand has increased for an improved display quality including the color display, high brightness and high resolution of the liquid crystal display apparatuses used for information terminals. In particular, uniform distribution of brightness in a plane has come to be in strong demand. However, in view of the fact that the light having a wide angular distribution from a light source enters a rod-like photoconductor, the strength distribution of the light emitted from the exit plane of the rod-like photoconductor is not uniform, and the brightness tends to decrease in the neighborhood of the end portions of the exit plane of the rod-like photoconductor.